The world's two most expensive players were injured on international duty, but head coach Tuchel suggested on Friday that it was "possible" both would recover in time for a key Champions League match.
And after Neymar and Mbappe watched Edinson Cavani fire PSG to a 1-0 win over Toulouse, Tuchel revealed he is now even more confident of their involvement.
"I am more optimistic than yesterday [Friday] about Ney and Kylian," he told a news conference. "They will be able to train on Monday."
PSG also have Dani Alves fit again after a lengthy lay-off, returning as a substitute against Toulouse, and Tuchel expects the full-back to be keen to feature in midweek.
"In theory [Alves] would not play on Wednesday as he has just returned from injury," Tuchel said. "But if you asked him, he would tell you, 'Yes'.
"He has returned to the team and he could play a match of that level against Liverpool."
Although the Ligue 1 champions were far from convincing on Saturday, goalscorer Cavani was glad to get the result and move on.
"We won, that's the most important," Cavani told Canal +. "Sometimes we play better and sometimes not, but we were up against a Toulouse team that played well defensively.
"There are things we can improve, but we needed to get the three points and to keep winning. Now it's finished. We need to prepare well for Liverpool, which is a big match."